The present invention relates to an image processing system, projector, program, information storage medium and image processing method which can regulate the luminance value of an image.
In recent years, image display devices such as a projector and the like have been designed to regulate the color and brightness of a displayed image depending on its display contents provided by a movie, game, PC (Personal Computer) or the like.
In such image display devices, the whole image is corrected uniformly.
In fact, however, an appropriate image cannot be displayed by uniformly correcting the whole image since the luminance value in the marginal portion of the displayed image is reduced depending on the properties of light source and projection lens.
For example, Japanese Patent Application No. Hei 4-134914 (Japanese Patent Application Laid-Open No. Hei 5-323892) discloses a uniformity circuit for overcoming such a problem. The uniformity circuit is designed to modulate R, G and B primary color video signals by the use of uneven-color correcting wave-shaped signals, thereby controlling R, G and B beam amperages flowing in CRT to control the luminance output on the CRT phosphor screen. This provides uniform R, G and B illumination distributions on the screen.
However, this uniformity circuit can only suppress the reduction of luminance in the marginal image portion as the result of uneven-color correction. This Japanese Patent Application discloses no concrete technique of correcting the uneven color for suppressing the reduction of luminance in the marginal image portion.
Moreover, it cannot be said that the complete correction of uneven color directly improves the image quality. It is important that the image is regulated depending on the displayed contents, rather than the correction.